Each of the 14 environment-related mathematics activities included in this publication by the Upper Mississippi River ECO-Center includes objectives, materials needed, preparation, and activity description. Occasionally, variations and helpful hints are added. Because the student can gain experience to help him with the practical application of abstract concepts by studying mathematics outdoors, special emphasis is given to the experiential study of metrics and the magnetic compass. The overall focus of the activities is on the use of mathematics in real life situations. Metrics activities include body measurements, pacing and measuring distances, and estimating heights. Compass activities include an introduction to the use of the magnetic compass, geometric figures, an introduction to mapping, constructing/teaching mapping courses, and games. In addition there are pollution, energy, and nature studies. The activities are designed to enhance elementary and junior high school students' awareness of mathematics found in nature, such as geometric shapes, and to teach metrics, the compass, and applied mathematics. This is the third in the series of environmental activities booklets by the ECO-Center, and is also related to their inservice Teaching Manual for environmental education. (SB)